6.1 Filtration
Metrohm 838 Advanced Sample Processor
,
Annex
67
6 Annex
6.1 Filtration
6.1.1 Selection of possible sample types
Each filtration process using a filtration membrane with a small pore
size could be subject to a membrane blockage.
The following table lists some types of sample that have been filtered
with the Metrohm 6.2729.110 Ultrafiltration Cell with the standard
6.2714.020 Filtration membrane (0.15
μ
m) or a second filter membrane
(0.2
μ
m) and then analyzed on a Metrohm IC system. The concentra-
tions of the following 7 anions were determined: F
-
, Cl
-
, NO
2
-
, Br
-
, NO
3
-
,
HPO
4
2-
, SO
4
2-
.
Sample type
Pore size
of membrane
No. of samples
per filter
Orange juice with fruit pulp
0.15
40
Surface water
0.15
500
Drinking water
0.15
1000
Ground water
0.15
500
Wastewater 1
0.15
1000
Wastewater 2
0.15
130
Wastewater 3
0.15
40
Wastewater 4
0.15
80
NaCl solution (1%)
0.2
5000
Schöninger digestion soln.
0.2 100
Acidic soil extracts
0.2 1000
Aqueous soil extracts
0.2 200
Table 6 Filtering various samples
The given number of samples that can be filtered on a filter membrane
without any loss of quality being observed are empirical values. They
have been determined at Metrohm AG and by various customers and
should be used as an orientation guide for estimating the application of
the ultrafiltration cell for sample preparation. These values must be de-
termined individually for each new application.
